Note: Some class sets have been added 1-3 items (Wrist, Gloves and Belt) to their set in the Sets interface. These items are not new items, but existing items that matched the missing pieces of the set and were added to this achievement set. These items drop from bosses in these raids (according to the Sets interface).

Comment by colarama

To be clear, the five-piece tier set is not enough for the achievement, you have to grind out the wrist, gloves and belt. These are not guaranteed drops, drop from different bosses for different classes, and cannot be purchased with tokens, making this a potentially painful grind. Check out your appearance set gui to check locations. Note that for most tier pieces the current GUI unhelpfully just says "vendor" instead of the tier drops, but the non-tier pieces will provide a boss.

I've personally been grinding Kara for six weeks trying to get my wrists to drop from Attumen with no luck. The only good news is that it's slightly less RNG dependent than tier 1 and tier 2.

And as mentioned in another post this is simply not possible to get the achievement at this time on DK, Monk or DH.

Comment by EmberDione

So just in case you are a doofus like me and trying to figure out why you don't have the achievement after getting the pieces....

Make sure you have sold them back or it's after the 2 hour window. (You have to perma learn them.)